The invention relates to an oil recovery process in which an aqueous solution which contains enough water-soluble anionic polysaccharide polymer to reduce its mobility is injected into a subterranean reservoir to displace fluid toward a production well or production location.
With respect to such oil recovery processes, it is known to use water-soluble anionic polysaccharide polymers as the mobility reducing agents. Various modifications of such polymers or solutions have been suggested. For example, U.S. Pat. No. 3,208,518 suggests that the pH of such a polymer solution be reduced to reduce the solution viscosity during injection and then be allowed to rise to increase the viscosity within the reservoir. U.S. Pat. No. 3,343,601 suggests that flood water be deoxygenated by adding a water-soluble hydrosulfite before or after adding a water-thickening polymer. U.S. Pat. No. 3,581,824 suggests that, within the reservoir, such a polymer solution be contacted with an aqueous solution of relatively high divalent cation concentration to cause agglomeration of the polymer for selectively plugging portions of the reservoir. U.S. Pat. No. 3,676,494 describes how to make novel sulfur-containing aromatic carboxylic acid amides and indicates that they can stabilize oxygen-sensitive organic materials against oxidation. U.S. Pat. No. 3,801,502 suggests that the viscosity increasing capability of Xanthan gum polymers be increased by adding, to their fermentation broths or effluents, various materials, inclusive of water-soluble alcohols. In SPE Paper No. 5372 presented at the April 1975 meeting in Ventura, California, and in U.S. Pat. No. 3,966,618, it is suggested that the filtration properties of Xanthan gum polymer solutions be improved by treating them with enzymes that solubilize the cellular debris of the bacterially-produced polymer.